POSIX support limitations

KasperskyOS has a limited implementation of POSIX oriented toward the POSIX.1-2008 standard. These limitations are primarily due to security precautions.

There is no XSI support or optional functionality.

Limitations affect the following:

Limitations include:

In KasperskyOS, signals cannot interrupt the Call(), Recv(), and Reply() system calls that support the operation of libraries that implement the POSIX interface.

The KasperskyOS kernel does not transmit signals.

Limitations on interaction between processes

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

fork()

Create a new (child) process.

Not implemented

unistd.h

pthread_

atfork()

Register the handlers that are called before and after the child process is created.

Not implemented

pthread.h

wait()

Wait for the child process to stop or complete.

Stub

sys/wait.h

waitid()

Wait for the state of the child process to change.

Not implemented

sys/wait.h

waitpid()

Wait for the child process to stop or complete.

Stub

sys/wait.h

execl()

Run the executable file.

Stub

unistd.h

execle()

Run the executable file.

Stub

unistd.h

execlp()

Run the executable file.

Stub

unistd.h

execv()

Run the executable file.

Not implemented

unistd.h

execve()

Run the executable file.

Not implemented

unistd.h

execvp()

Run the executable file.

Stub

unistd.h

fexecve()

Run the executable file.

Stub

unistd.h

setpgid()

Move the process to another group or create a group.

Stub

unistd.h

setsid()

Create a session.

Stub

unistd.h

getpgrp()

Get the group ID of the calling process.

Stub

unistd.h

getpgid()

Get the group ID.

Stub

unistd.h

getppid()

Get the ID of the parent process.

Stub

unistd.h

getsid()

Get the session ID.

Stub

unistd.h

times()

Get the time values for the process and its descendants.

Stub

sys/times.h

kill()

Send a signal to the process or group of processes.

Only the SIGTERM signal can be sent. The pid parameter is ignored.

signal.h

pause()

Wait for a signal.

Stub

unistd.h

sigpending()

Check for received blocked signals.

Not implemented

signal.h

sigqueue()

Send a signal to the process.

Not implemented

signal.h

sigtimedwait()

Wait for a signal from the defined set of signals.

Not implemented

signal.h

sigwaitinfo()

Wait for a signal from the defined set of signals.

Not implemented

signal.h

sem_init()

Create an unnamed semaphore.

You cannot create an unnamed semaphore for synchronization between processes. If a non-zero value is passed through the pshared parameter, it will return only the value -1 and will assign the ENOTSUP value to the errno variable.

semaphore.h

sem_open()

Create/open a named semaphore.

You cannot open a named semaphore that was created by another process. Named semaphores (like unnamed semaphores) are local, which means that they are accessible only to the process that created them.

semaphore.h

pthread_

spin_init()

Create a spin lock.

You cannot create a spin lock for synchronization between processes. If the PTHREAD_PROCESS_SHARED value is passed through the pshared parameter, this value will be ignored.

pthread.h

mmap()

Map to memory.

You cannot perform memory mapping for interaction between processes. If the MAP_SHARED and PROT_WRITE values are passed through the flags and prot parameters, respectively, it will return only the MAP_FAILED value and will assign the EACCES value to the errno variable. For all other possible values of the prot parameter, the MAP_SHARED value of the flags parameter is ignored. In addition, you cannot pass combinations of the PROT_WRITE|PROT_EXEC and PROT_READ|PROT_WRITE|PROT_EXEC flags through the prot parameter. In this case, it will return only the MAP_FAILED value and will assign the ENOMEM value to the errno variable.

sys/mman.h

mprotect()

Define the memory access permissions.

For security purposes, some configurations of the KasperskyOS kernel prohibit granting simultaneous write-and-execute access to virtual memory regions. If this type of kernel configuration is in use and you pass the PROT_WRITE|PROT_EXEC value through the prot parameter, it will only return the -1 value and will assign the ENOTSUP value to the errno variable.

sys/mman.h

pipe()

Create an unnamed channel.

You cannot use an unnamed channel for data transfer between processes. Unnamed channels are local, which means that they are accessible only to the process that created them.

unistd.h

mkfifo()

Create a special FIFO file (named channel).

Stub

sys/stat.h

mkfifoat()

Create a special FIFO file (named channel).

Not implemented

sys/stat.h

Limitations on interaction between threads via signals

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

pthread_kill()

Send a signal to a thread.

You cannot send a signal to a thread. If a signal number is passed through the sig parameter, only the ENOSYS value is returned.

signal.h

siglongjmp()

Restore the state of the control thread and the signals mask.

Not implemented

setjmp.h

sigsetjmp()

Save the state of the control thread and the signals mask.

Not implemented

setjmp.h

Asynchronous input/output limitations

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

aio_cancel()

Cancel input/output requests that are waiting to be handled.

Not implemented

aio.h

aio_error()

Receive an error from an asynchronous input/output operation.

Not implemented

aio.h

aio_fsync()

Request the execution of input/output operations.

Not implemented

aio.h

aio_read()

Request a file read operation.

Not implemented

aio.h

aio_return()

Get the status of an asynchronous input/output operation.

Not implemented

aio.h

aio_suspend()

Wait for the completion of asynchronous input/output operations.

Not implemented

aio.h

aio_write()

Request a file write operation.

Not implemented

aio.h

lio_listio()

Request execution of a set of input/output operations.

Not implemented

aio.h

Limitations on the use of robust mutexes

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

pthread_mutex_consistent()

Return a robust mutex to a consistent state.

Not implemented

pthread.h

pthread_mutexattr_getrobust()

Get a robust mutex attribute.

Not implemented

pthread.h

pthread_mutexattr_setrobust()

Define a robust mutex attribute.

Not implemented

pthread.h

Terminal operation limitations

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

ctermid()

Get the path to the file of the control terminal.

Only returns or passes an empty string through the s parameter.

stdio.h

tcsetattr()

Define the terminal settings.

The input speed, output speed, and other settings specific to hardware terminals are ignored.

termios.h

tcdrain()

Wait for output completion.

Returns only the value -1.

termios.h

tcflow()

Suspend or resume receipt or transmission of data.

Suspending output and resuming suspended output are not supported.

termios.h

tcflush()

Clear the input queue or output queue, or both of these queues.

Returns only the value -1.

termios.h

tcsendbreak()

Break the connection with the terminal for a set time.

Returns only the value -1.

termios.h

ttyname()

Get the path to the terminal file.

Returns only a null pointer.

unistd.h

ttyname_r()

Get the path to the terminal file.

Returns only an error value.

unistd.h

tcgetpgrp()

Get the ID of a group of processes using the terminal.

Returns only the value -1.

unistd.h

tcsetpgrp()

Define the ID for a group of processes using the terminal.

Returns only the value -1.

unistd.h

tcgetsid()

Get the ID of a group of processes for the leader of the session connected to the terminal.

Returns only the value -1.

termios.h

Shell operation limitations

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

popen()

Create a child process for command execution and an unnamed channel with this process.

Only assigns the ENOSYS value to the errno variable and returns the NULL value.

stdio.h

pclose()

Close the unnamed channel with the child process created by popen(), and wait for the child process to terminate.

Cannot be used because popen() always returns NULL instead of the handle of the unnamed channel that serves as an input parameter for pclose().

stdio.h

system()

Create a child process for command execution.

Stub

stdlib.h

wordexp()

Perform a shell-like expansion of the string.

Not implemented

wordexp.h

wordfree()

Free up the memory allocated for the results from calling wordexp().

Not implemented

wordexp.h

Limitations on file handle management

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

dup()

Make a copy of the handle of an opened file.

Handles of regular files, standard I/O streams, sockets and channels are supported. There is no guarantee that the lowest available handle will be received.

fcntl.h

dup2()

Make a copy of the handle of an opened file.

Handles of regular files, standard I/O streams, sockets and channels are supported. The handle of an opened file needs to be passed through the fildes2 parameter.

fcntl.h

Limitations on clock usage

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

clock_gettime()

Get the time value.

If the CLOCK_PROCESS_CPUTIME_ID value or CLOCK_THREAD_CPUTIME_ID value is passed through the clock_id parameter, it will return only the value -1 and will assign the EINVAL value to the errno variable.

time.h

clock()

Get the CPU time spent on execution of the calling process.

Returns the amount of time (in milliseconds) that has elapsed since the KasperskyOS kernel was started.

time.h

Getting system parameters

Interface

Purpose

Implementation

Header file based on the POSIX.1-2008 standard

confstr()

Get a system parameter.

Stub

unistd.h

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